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2020-05-11 08:49:43 -06:00
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common/src/lx_nor_flash_driver_read.c
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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** LevelX Component */
/** */
/** NOR Flash */
/** */
/**************************************************************************/
/**************************************************************************/
#define LX_SOURCE_CODE
/* Disable ThreadX error checking. */
#ifndef TX_DISABLE_ERROR_CHECKING
#define TX_DISABLE_ERROR_CHECKING
#endif
/* Include necessary system files. */
#include "lx_api.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _lx_nor_flash_extended_cache_read PORTABLE C */
/* 6.0 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function performs a read of the NOR flash memory. */
/* */
/* INPUT */
/* */
/* nor_flash NOR flash instance */
/* flash_address Address of NOR flash to read */
/* destination Destination for the read */
/* words Number of words to read */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* (lx_nor_flash_driver_read) Actual driver read */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* */
/**************************************************************************/
UINT _lx_nor_flash_driver_read(LX_NOR_FLASH *nor_flash, ULONG *flash_address, ULONG *destination, ULONG words)
{
#ifndef LX_NOR_DISABLE_EXTENDED_CACHE
UINT status;
UINT i;
ULONG *cache_entry_start;
ULONG *cache_entry_end;
ULONG cache_offset;
UINT least_used_cache_entry;
/* Is the request a whole sector or a partial sector. */
if ((words == 1) && (nor_flash -> lx_nor_flash_extended_cache_entries))
{
/* One word request, which implies that it is a NOR flash metadata read. */
/* Initialize the least used cache entry. */
least_used_cache_entry = 0;
do
{
/* Loop through the cache entries to see if there is a sector in cache. */
for (i = 0; i < nor_flash -> lx_nor_flash_extended_cache_entries; i++)
{
/* Search through the cache to find the entry. */
/* Determine the cache entry addresses. */
cache_entry_start = nor_flash -> lx_nor_flash_extended_cache[i].lx_nor_flash_extended_cache_entry_sector_address;
cache_entry_end = cache_entry_start + LX_NOR_SECTOR_SIZE;
/* Determine if the flash address in in the cache entry. */
if ((cache_entry_start) && (flash_address >= cache_entry_start) && (flash_address < cache_entry_end))
{
/* Yes, we found the entry. */
/* Increment the accessed count. */
nor_flash -> lx_nor_flash_extended_cache[i].lx_nor_flash_extended_cache_entry_access_count++;
/* Calculate the offset into the cache entry. */
cache_offset = (ULONG)(flash_address - cache_entry_start);
/* Copy the word from the cache. */
*destination = *(nor_flash -> lx_nor_flash_extended_cache[i].lx_nor_flash_extended_cache_entry_sector_memory + cache_offset);
/* Increment the number of cache hits. */
nor_flash -> lx_nor_flash_extended_cache_hits++;
/* Return success. */
return(LX_SUCCESS);
}
else
{
/* Determine if we have a new least used sector. */
if (i != least_used_cache_entry)
{
/* Determine if this entry has a smaller accessed count. */
if (nor_flash -> lx_nor_flash_extended_cache[i].lx_nor_flash_extended_cache_entry_access_count <
nor_flash -> lx_nor_flash_extended_cache[least_used_cache_entry].lx_nor_flash_extended_cache_entry_access_count)
{
/* New least used entry. */
least_used_cache_entry = i;
}
}
}
}
/* Now read in the sector into the cache. */
cache_offset = (ULONG)(flash_address - nor_flash -> lx_nor_flash_base_address);
cache_offset = cache_offset & ~((ULONG) (LX_NOR_SECTOR_SIZE-1));
cache_entry_start = nor_flash -> lx_nor_flash_base_address + cache_offset;
/* Call the actual driver read function. */
status = (nor_flash -> lx_nor_flash_driver_read)(cache_entry_start,
nor_flash -> lx_nor_flash_extended_cache[least_used_cache_entry].lx_nor_flash_extended_cache_entry_sector_memory,
LX_NOR_SECTOR_SIZE);
/* Determine if there was an error. */
if (status != LX_SUCCESS)
{
/* Return the error to the caller. */
return(status);
}
/* Setup the cache entry. */
nor_flash -> lx_nor_flash_extended_cache[least_used_cache_entry].lx_nor_flash_extended_cache_entry_sector_address = cache_entry_start;
nor_flash -> lx_nor_flash_extended_cache[least_used_cache_entry].lx_nor_flash_extended_cache_entry_access_count = 0;
/* Increment the number of cache misses. */
nor_flash -> lx_nor_flash_extended_cache_misses++;
/* Decrement the number of cache hits, so that the increment that will happen next will be cancelled out. */
nor_flash -> lx_nor_flash_extended_cache_hits--;
} while (status == LX_SUCCESS);
/* Return success. */
return(LX_SUCCESS);
}
else
{
/* Call the actual driver read function. */
status = (nor_flash -> lx_nor_flash_driver_read)(flash_address, destination, words);
/* Return completion status. */
return(status);
}
#else
UINT status;
/* Call the actual driver read function. */
status = (nor_flash -> lx_nor_flash_driver_read)(flash_address, destination, words);
/* Return completion status. */
return(status);
#endif
}